Mike Riordan played for PC in the latter years of the Joe Mullaney era, averaging 11.2 points and 8.2 points from 1964-1967. Riordan was a key member of two NCAA Tournament teams during his time at Providence. In his junior season, Riordan posted averages of 10.3 points and 9.1 rebounds during the Friars run to the Elite Eight.

Riordan was selected in the 12th round of the 1967 NBA Draft by the New York Knicks. He played nine seasons (1968-1977) in the National Basketball Association as a member of the Knicks and Baltimore/Capital/Washington Bullets. He scored 6,334 points in his career and won an NBA Championship with the Knicks in 1970. In 1972-73, Riordan averaged 18.1 points, 4.9 rebounds and 5.2 assists in leading the Baltimore Bullets to a Central Division title and playoff appearance. He was named to the NBA All-Defensive Second Team in 1973. In the 1975-76 season, Riordan averaged 15.4 points per game and led the Bullets to the Eastern Conference Finals and a 60-22 record.